This invention relates to a power driven hair clipper.
A power driven hair clipper of the type initially referred to is known from U.S. Pat. No. 2,741,026. The cutting head, formed by an outer blade and an inner cutting blade driven to oscillate, is rigidly fastened to the yoke arms of the casing head constructed in a U-shaped configuration. The arcuate shape of the outer blade with its two rows of cutting teeth permits the hair clipper and the outer blade fastened thereto to execute a restricted pivot movement of 9xc2x0, while the relatively large distance of the cutting head""s row of teeth used at a time to the biggest diameter of the hair clipper""s casing is intended to enable both rows of teeth to be used for trimming purposes.
A power driven hair clipper of the type initially referred to is also known from U.S. Pat. No. 1,997,096, having a cutter head mounted for pivotal motion into corresponding positions for shaving and trimming, comprising a supporting element mounted for controlled pivotal motion along a curved track, a comb plate with only one row of teeth, and a cutter blade held in engagement with the comb plate by means of a resilient tension plate resting on the supporting element. An actuating element extending from the upper end of the casing transmits the driving motion to the cutter blade. A friction element acted upon by a spring element is arranged in the supporting element in such a way that it is urged against the upper surface of the hair clipper""s casing in order to hold the cutter head in any given pivot position by frictional pressure engagement.
From GB 2 294 230 there is known a power driven hair clipper with a cutter head mounted for pivotal motion in all directions, whose pivotability is assured by a ball and socket connection between the housing and the cutter head. The cutter head, comprised of a supporting element and a housing cover member, includes a pair of blades, each equipped with two rows of cutting teeth extending parallel to each other but arranged in the cutter head in such a way that only one of the cooperating rows of cutting teeth on the pair of blades projects out of the cutter head housing. For the second row of cutting teeth to be brought into use, the cutter head has to be opened to enable the pair of blades to be turned through 180xc2x0 inside the cutter head.
It is an object of the present invention to improve a power driven hair clipper of the type initially referred to in respect of its function and facilitate its handling.
The present invention has several advantages. One of these advantages is that the components provided for driving the clipper blade which include, for example, the bearing bracket, the clipper blade carrier with coupling elements, the locking device and the detent device, are largely encapsulated by means of the supporting element formed as a housing shell in order to prevent clipped hairs from directly entering this working area. The housing shell also enables a locking device to be arranged for fastening and removing the clipper head for cleaning and maintenance purposes, thus also making it easier to replace.
A further essential advantage of the invention results from the geometric form of the housing shell pivotally mounted on the yoke arms of the housing, and of the adjacent housing wall of the housing. The outer contour of the housing shell provided for by the invention guarantees a relatively close fit to the inner contour of the wall of the housing over the total pivot range of the housing shell. The distance between the outer contour of the housing shell and the inner contour of the wall of the housing can be selected so small that a smooth pivoting movement of the housing shell is guaranteed while, in addition, the ingress of clipped hairs into the interior of the housing is prevented. A distance of one tenth of a millimeter between the inner contour of the wall of the housing and the outer contour of the housing shell is already sufficient for a smooth pivoting movement of the clipper head and, for example, to prevent hair getting into the interior of the housing.
The operative association of two clipper blades to one clipper comb advantageously enables the rows of teeth formed by the teeth of the clipper comb and of the two clipper blades to be differently constructed, for example by having the length of extension of one row of cutting teeth significantly smaller than the length of extension of the other row of cutting teeth. Different constructions of this type guarantee that the hair clipper is put to optimal use by putting into operation the cutting teeth row best suited for the particular clipping operation. For example, clipping operations in hard to reach areas can be performed far more easily and simply with a row of cutting teeth with a smaller length of extension than with a bigger or relatively large length of extension. By contrast, cutting teeth rows with larger lengths of extension are particularly well suited for cutting contours.
A preferred embodiment of the invention is characterized in that one wall of the housing shell is definable by a circumferential surface of the sector of the circular cylinder with a radius starting from the pivot axis.
According to a further embodiment of the invention provision is made for one wall of the housing shell to be formed by the circumferential surface of two combined sectors of circular cylinders.
In a further aspect of this embodiment provision is made for the radii of the respective sectors of the circular cylinders to be of equal size. An advantage of this provision is that the volume of the housing shell available for covering clipper parts and drive elements with the housing shell is relatively amply dimensioned.
According to a further advantageous embodiment provision is made for the radii of the respective sectors of the circular cylinders to be of different size. This provision of the invention has several advantages. The different radii of the respective sectors of the circular cylinders produce a geometric form of the housing shell, in which the outer contour of the circumferential surfaces or wall of the housing shell is recessed in step shape. This step-shaped shoulder can be used, for example, as a limit stop for limiting the pivot movement of the housing shell and hence of the clipper head of the hair clipper. A further effect of this provision is that the drive elements and the clipping parts of the clipper head are closely encapsulated without any unnecessary loss of space. The space thus gained can be used, for example, to arrange further components inside the housing of the hair clipper.
According to a preferred embodiment of the invention provision is made for different lengths of extension of the circumferential surfaces of the respective sectors of the circular cylinders on the housing shell edge.
According to an advantageous embodiment of the invention provision is made for the cutting teeth rows of the clipper head to have different lengths of extension, thus enabling the optimal length of a cutting teeth row to be selected for the particular use. In a further aspect of this embodiment provision is made for the lengths of extension of the circumferential surfaces to be essentially adapted to the lengths of extension of the cutting teeth rows.
In yet another aspect of this embodiment provision is made for the geometric form of each end wall to be formed by at least two conical surfaces with different cone angles relative to the pivot axis. A particularly simple bearing arrangement of the housing shell on the wall of the housing is characterized in that one end of the conical surface of the housing shell leading to the pivot axis is constructed as a truncated cone with a bearing surface intersecting the pivot axis at right angles.
The geometric form of the inner contour of the wall of the housing is shaped to conform to the outer contour of the wall of the housing shell. This adaptation permits a variety of embodiments. According to a preferred embodiment of the invention provision is made for the conical surface of the end wall to be constructed in arcuate shape. According to a further preferred embodiment of the invention provision is made for the outer contour of the wall of the housing shell to be constructed in rectilinear and/or arcuate shape. To accommodate this geometrical construction of the housing shell provision is made in a further advantageous embodiment of the invention for the inner contour of the wall of the housing receiving the housing shell to be constructed in a rectilinear and/or arcuate shape.
A preferred embodiment of the invention is characterized in that the end of the housing is of a yoke-shaped construction and that the housing shell is pivotally mounted on the yoke arms of the housing by means of a pivot bearing.